This invention relates to an improved drive unit for conveyors for materials of fluid behaviour, such as feed metarials in livestock rearing stations, where the conveyor is of the type comprising a cable on which there are fitted spaced-apart conveying elements in the form of discs or fins, the cable being made to slide endlessly inside a tube so as to discharge the feed material into feeding troughs from which the animals eat.
As is well known to experts in this particular art, one of the problems to be solved in designing systems of this kind is the problem of tension variations in the cable. The degree of cable tension is subject to variation both during the operation of the system due to variations in the load applied to it, and by virtue of the elongation which occurs with time, and which is particularly felt in systems of a certain length.
In seeking to automatically take-up these cable tension variations, the main approach has been to provide deviation pulleys mounted in a floating manner and subjected to the action of return springs or counter-weights.
However, such arrangements have not given completely satisfactory results, in particular because they make the system drive unit rather bulky and more costly.